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150FD ENGINE
Owner's Manual
Page 15/36
PRE-OPERATION INSPECTION AND MAINTENANCE
CARBURETOR SETTING
The carburetor is extremely sensitive to foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign matter to get into the carburetor.
Always handle the carburetor and its components carefully. Even slight scratches, bends or
damage to carburetor parts may prevent the carburetor from functioning correctly.
Carefully perform all servicing with the appropriate tools and without applying excessive
force.
After installing the carburetor, check that the throttle operates correctly and opens and
closes smoothly.
It is highly recommended that the carburetor setting is performed by an experienced
mechanic to obtain the best possible performance.
Atmospheric conditions and carburetor settings
The air density (i.e., concentration of oxygen in the air) determines the richness or leanness
of the air/fuel mixture. Therefore, refer to the above table for mixture settings.
That is:
Higher temperature expands the air with its resultant reduced density.
Higher humidity reduces the amount of oxygen in the air by so much of the water vapor
in the same air.
Lower atmospheric pressure (at a high altitude) reduces the density of the air.
Air Temp.
Humidity
Air Pressure
(Altitude)
Mixture
Setting
High
High
Low
(High)
Richer
Leaner
Low
Low
High
(Low)
Leaner
Richer
